Electrified vehicles employ an electric drive system configured to provide propulsion to assist or replace that provided by an internal combustion engine. The electric drive system typically includes a high voltage energy storage device, such as a high voltage battery, coupled by high voltage buses to a power conversion system that provides alternating current to an electric motor. A high voltage battery can comprise a plurality of electrically connected battery cells. Insufficient cell charge, or impaired connections between cells, can diminish the voltage provided by the battery. Battery drainage caused by small leakage currents or by high voltage domain short circuits can also impair battery performance.
Therefore; an electrified vehicle is equipped with a leakage detection circuit designed to detect and gauge the amount of current leakage present. A leakage detection circuit is typically in the form of either an ohmic circuit, in which a voltage across a detection resistor indicates the presence of leakage current, or an AC circuit, in which a change in impedance between high and low voltage domains indicates the existence of leakage current. Because leakage detection capability at an electrified vehicle is important, many leakage detection circuits are accompanied by a robustness check circuit designed to determine whether the leakage detection circuit is functional.